The present invention relates to a novel hydrogenated ring-opening metathesis polymer, more particularly, relates to a hydrogenated ring-opening metathesis polymer suitable for a base polymer of a photoresist used in fine working of a semiconductor using ultraviolet ray and far ultraviolet ray (including excimer laser and the like), excellent in heat resistance, thermal decomposition resistance, light transmittance and the like, and a method of producing the polymer hydrogen-added material.
With the recent increase of integration level in integrated circuits on semiconductor devices, and large-scale integrated circuits (LSI) and very-large-scale integrated circuits (VLSI) have been put to practical use, and additionally, the minimum lithographic pattern in an integrated circuit would be reaching in submicron feature, in future there is a tendency of further microlithographic. Formation of a microlithographic pattern essentially requires use of a lithographic technology in which a treated substrate on which a thin film is formed is coated with a resist material, selective exposure is effected to form a latent image of a desired pattern, then, development is conducted to form a resist pattern which is used as a mask in dry etching, then, the resist material is removed to obtain a desired pattern.
As the exposure light source used in this lithographic technology, ultraviolet lights such as g ray (wavelength: 436 nm) and i ray (wavelength: 365 nm) have been utilized, with the progress of the fine lithographic pattern, and exposure light having a shorter wavelength such as far ultraviolet ray, vacuum ultraviolet ray, electron beam (EB), X ray and the like have become popular to use as a light source. Particularly recently, excimer lasers (KrF laser having a wavelength of 248 nm, ArF laser having a wavelength of 193 nm) have received attention as an exposure light source, and are expected to be effective in formation of a fine lithographic pattern.
As polymers or copolymers used in a resist material forming a sub-micron pattern using exposure light in a region of vacuum ultraviolet ray manifesting shorter wavelengths, there have been suggested a lot of polymers and copolymers such as, for example, polymers or copolymers of a substituted acrylates or acrylates having an acid cleavable protecting group and an adamantane skeleton at an ester portion (see JP-A No. 4-39665), polymers or copolymers of a substituted acrylates or acrylates having an acid cleavable protecting group and a norbornane skeleton at an ester portion (see JP-A No. 5-257281), polymers or copolymers of cyclohexyl maleimide (see JP-A No. 5-257285), polymer compounds containing in the main chain a cellulose skeleton which is cleaved by the action of an acid (see JP-A No. 6-342212), polyvinyl alcohol or its derivatives (see JP-A No. 7-333850), and the like.
However, there is no polymer or copolymer yet which satisfies all of various properties necessary for use as a resist material such as dry etching resistance, transparency for far ultraviolet ray, solubility in resist solvent, wettability to a developer, adhesion to a substrate of silicon and the like, solubility in a releasing agent, and the like, and can be synthesized easily, requiring further developments.
On the other hand, cyclic polymers as found in photoresist compositions comprising a polymer compound having a cyclic skeleton which contains an alicyclic hydrocarbon as the main chain and has a pendant acid cleavable group (WO97/33198, JP-A Nos. 09-230595, 09-244247, 10-254139) have problems such as poor solubility in a resist solvent at high concentration, poor wettability to a developer, poor adhesion to a silicon substrate and the like, though these cyclic polymers are excellent in dry etching resistance and excellent in transparency to far ultraviolet ray.
An object of the present invention is to provide a hydrogenated ring-opening metathesis polymer which satisfies above-mentioned various properties necessary for use as a base polymer for a resist material, more particularly, all of various properties necessary for use as a base polymer for a resist material in a positive photoresist composition which is excellent in light transparency and the like, has high sensitivity and high resolution and has high affinity to an alkali developer, and provides an excellent pattern, to be used for fine working of a semiconductor using ultraviolet ray and far ultraviolet ray (including excimer laser and the like), and which further have a narrower molecular weight distribution, and to provide a method of producing such a polymer hydrogen-added material.
The present inventors have studied variously for solving the above-mentioned problems and intensively investigated a possibility of use of a hydrogenated ring-opening metathesis polymer of a cyclic olefin-based monomer as a base polymer for a resist material having excellent optical property, electric property, rigidity, heat resistance, adhesion to a substrate, and weather resistance, and resultantly found that a novel hydrogenated ring-opening metathesis polymer having a specific structural unit, namely, a structural unit which has an alicyclic compound as the main chain and contains an oxygen atom in a part of the cyclic structure thereof satisfies these various abilities as a resist material, leading to completion of the invention.
Namely, the present invention provides a hydrogenated ring-opening metathesis polymer which contains, if necessary, a structural unit [A] of the following general formula [1]: 
[wherein, at least one of R1 to R4 represents a functional group having a tertiary ester group of a cyclic alkyl of the following general formula [2]: 
(wherein, the chain fine represents a connecting means. R5 represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, a linear, branched or cyclic alkoxylalkyl group having 2 to 10 carbon atoms, or a linear, branched or cyclic acyl group having 1 to 10 carbon atoms. R6 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. W1 represents a single bond or a (k+2)-valent hydrocarbon group having 1 to 10 carbon atoms. Z represents a divalent hydrocarbon group having 2 to 15 carbon atoms, and forums a single ring or a cross-linked ring together with carbon atoms to be bonded. k represents 0 or 1.) and the remaining groups of R1 to R4 are selected each independently from a hydrogen atom, linear, branched or cyclic alkyl groups having 1 to 20 carbon atoms, halogens, linear, branched or cyclic halogenated alkyl groups having 1 to 20 carbon atoms, linear, branched or cyclic alkoxy groups having 1 to 20 carbon atoms, linear, branched or cyclic alkoxyalkyl groups having 2 to 20 carbon atoms, linear, branched or cyclic alkylcarbonyloxy groups having 2 to 20 carbon atoms, arylcarbonyloxy groups having 6 to 20 carbon atoms, linear, branched or cyclic alkylsulfonyloxy groups having 1 to 20 carbon atoms, arylsulfonyloxy groups having 6 to 20 carbon atoms, linear, branched or cyclic alkoxycarbonyl groups having 2 to 20 carbon atoms, or linear, branched or cyclic alkoxycarbonylalkyl groups having 3 to 20 carbon atoms, end X1s may be the same or different and represent xe2x80x94Oxe2x80x94 or xe2x80x94CR72xe2x80x94 (wherein, R7 represents a hydrogen atom ore linear or branched alkyl group having 1 to 10 carbon atoms.). j represents an integer of 0 or 1 to 3.], and contains at least a structural unit [B] of the following general formula [3]: 
[wherein, R8 to R11 each independently represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and X2s may be the same or different and represent xe2x80x94Oxe2x80x94 or xe2x80x94CR122xe2x80x94 (wherein, R12 represents a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms.). m represents an integer of 0 or 1 to 3.], and/or a structural unit [C] of the following general formula [4]: 
[wherein, R13 to R16 each independently represent a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and X3s may be the same or different and represent xe2x80x94Oxe2x80x94 or xe2x80x94CR172xe2x80x94 (wherein, R17 represents a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms.). One of Y1 and Y2 represents xe2x80x94(Cxe2x95x90O)xe2x80x94 and the other of Y1 and Y2 represents xe2x80x94CR182xe2x80x94 (wherein, R18 represents a hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms.). n represents an integer of 0 or 1 to 3.],
wherein at least one of X1 in the structural unit [A] of the general formula [1], X2 in the structural unit [B] of the general formula [3] and X3 in the structural unit [C] of the general formula [4] represents xe2x80x94Oxe2x80x94, and
the molar ratio of [A]/([B] and [C]) is 0/100 to 99/1, and the ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn (Mw/Mn) is 1.0 to 2.0.
Further, the present invention provides a method of producing a hydrogenated ring-opening metathesis polymer according to claim 1, comprising
using, if necessary, a cyclic olefin monomer of the following general formula [9]: 
(wherein, R1 to R4, X1 and j are as defined above.) and, at least a cyclic olefin monomer of the following general formula [10]: 
(wherein, R8 to R11, X2 and m are as defined above.) and/or a cyclic olefin monomer of the following general formula [11]: 
(wherein, R13 to R16, X3, Y1, Y2 and n are as defined above.), wherein at least one of X1 in the general formula [9], X2 in the general formula [10] and X3 in the general formula [11] represents xe2x80x94Oxe2x80x94, and
polymerizing these monomers with a ring-opening metathesis catalyst, and hydrogenating the resulted polymer in the presence of a hydrogenation catalyst.